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I have to admit up front this is a borderline shopping question. But the fact is I'm looking at an application note from Linear Technologies. That application note calls for Coiltronics CTX02-14659 for the isolating DC-DC transformer. What are the salient properties of this transformer I should be considering when looking for substitutes? I don't work with transformers regularly so this is all a bit foreign to me. If possible, I'd rather not get backed into a corner on having a single supplier for this part, so how do I go about finding an acceptable substitute parametrically.

vicatcu
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Consider winding your own: -

The coiltronic spec tells you the primary inductance and turns ratios. Choose a ferrite that is lowish loss at YOUR operating frequency. The ferrite chosen will have an A(L) value which basically tells you how many turns you need to wind to get the inductance of the primary. Secondaries are factored from the primary turns with the turns ratio.

Notice the voltage testing they have done to prove the isolation - this can be emulated with layers of polyester or PTFE tape or maybe consider a toroid where the windings are spaced apart BUT the ferrite is still potentially conductive so you will need insulation but only half the amount per winding.

Once you have got your head around this it will allow you review other manufacturer's offerings.

Andy aka
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  • the operating frequency is definitively 400kHz in this application... – vicatcu Apr 28 '13 at 14:58
  • You don't have to wind your own but if you go through the process of pretending you do by picking a ferrite core then picking the ferrite material to suit the frequency of operation you'll learn the ropes to be able to look at other potential suppliers. 400kHz - 3F3 or 3F4 material from Ferroxcube sound the right sort of materials. Maybe that's a good starting point - look up the material specs - you'll see graphs of "standard" permeability against frequency with a loss curve superimposed. Permeability translates to inductance. – Andy aka Apr 28 '13 at 15:26